One-pack epoxy resin composition, one-pack corrosion resistant paint composition, and coating method using said compositions

ABSTRACT

The present invention provides: 
     (1) a one-packed epoxy resin composition comprising 
     (A) an epoxy resin having two or more epoxy groups in its molecule and a number average molecular weight of 250 to 4,500, 
     (B) a ketimine compound, 
     (C) a dehydrating agent, and 
     (D) at least one modified epoxy resin (d-1) selected among urethane-modified epoxy resins, amine-modified epoxy resins and dimer-modified epoxy resins and/or a resin (d-2) which has a softening point of 60° C. or above and is at least one member selected among xylene resins, ketone resins, coumarone resins and petroleum resins; 
     (2) a one-packed anticorrosive paint composition comprising the above one-packed epoxy resin composition and (E) a zinc dust in such an amount as to be present in a proportion of 20 to 95 wt. % in the heat-cured coating film; and 
     (3) a coating method comprising the steps of undercoating the surface of a substrate and conducting topcoating, wherein the above one-packed epoxy resin composition or the above anticorrosive paint composition is used as the undercoating composition.

FIELD OF THE INVENTION

The present invention relates to a novel one-packed epoxy resincomposition and a one-packed anticorrosive paint composition which haveexcellent storage stability and are capable of forming coatingsexcellent especially in adhesion and drying characteristics, and acoating method using the compositions.

BACKGROUND ART

Epoxy resins have been used in various fields such as coatingcompositions, sealing agents, adhesives and the like, because of theirexcellent properties, in particular, their high adhesion. However, mostof conventionally used epoxy resin compositions are two-packedcompositions consisting of a main agent and a curing agent. Since thecuring reaction starts immediately after mixing the main agent andcuring agent, the two-packed epoxy resin compositions have a very shortpot life, resulting in poor workability.

Method were proposed for extending the pot life, for example by adding alatent curing agent such as blocked isocyanate to an epoxy resin.However, the latent curing agent is inherently of a heat-curing type,and is not practically usable for curing by ordinary temperature drying.The present applicant proposed in Japanese Examined Patent PublicationNo. 32231/1987 a method for preventing corrosion using a coatingcomposition comprising an epoxy resin, a ketimine compound and adehydrating agent. However, the composition, when used as a two-packedtype, has poor drying characteristics and a very low curing rate,although having a prolonged pot life. On the other hand, when thecomposition is used as a one-packed type, it has insufficient storagestability.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a one-packed epoxyresin composition and a one-packed anticorrosive paint composition whichare free from the above drawbacks of the prior art, and a coating methodusing the compositions.

Another object of the present invention is to provide a one-packed epoxyresin composition and a one-packed anticorrosive paint composition whichare excellent in storage stability, workability and the like and arecapable of forming coatings excellent in drying characteristics,overcoatability, adhesion and the like, and a coating method using thecompositions.

Other features of the invention will be apparent from the followingdescription.

The present invention provides:

(1) a one-packed epoxy resin composition comprising

(A) an epoxy resin having two or more epoxy groups in its molecule and anumber average molecular weight of 250 to 4,500,

(B) a ketimine compound,

(C) a dehydrating agent, and

(D) at least one modified epoxy resin (d-1) selected amongurethane-modified epoxy resins, amine-modified epoxy resins and dimeracid-modified epoxy resins, and/or a resin (d-2) which has a softeningpoint of 60° C. or above and is at least one member selected amongxylene resins, ketone resins, coumarone resins and petroleum resins;

(2) a one-packed anticorrosive paint composition comprising the aboveone-packed epoxy resin composition and (E) a zinc dust in such an amountas to be present in a proportion of 20 to 95 wt. % in the heat-curedcoating film; and

(3) a coating method comprising the steps of undercoating the surface ofa substrate and conducting topcoating, wherein the above one-packedepoxy resin composition or the above anticorrosive paint composition isused as the undercoating composition.

The present inventors carried out extensive research and found that theabove objects can be achieved when the above specified modified epoxyresin and/or xylene resin or like resin are mixed with a compositioncontaining an epoxy resin, a ketimine compound and a dehydrating agent.The present invention has been accomplished based on this novel finding.

The present invention will be described below in further detail.

The component (A) of the resin composition of the invention is an epoxyresin having two or more, preferably 2 to 5 epoxy groups in its moleculeand a number average molecular weight of about 250 to 4,500, preferablyabout 350 to 3,000. A suitable epoxy equivalent of the epoxy resin isabout 80 to 2,200, preferably 170 to 1,500.

Examples of the epoxy resin (A) include epoxy resins obtained byreacting a polyvalent alcohol, a polyvalent phenol or the like andexcess epichlorohydrin or by reacting excess epichlorohydrin with anadduct of a polyvalent alcohol, a polyvalent phenol or the like with analkylene oxide (such as ethylene oxide or propylene oxide). Examples ofthe polyvalent alcohol are ethylene glycol, polyethylene glycol,propylene glycol, neopentyl glycol, butylene glycol, hexanediol,glycerin, trimethylolethane, trimethylolpropane, pentaerythritol,diglycerol, sorbitol and the like. Examples of the polyvalent phenolinclude 2,2-bis(4-hydroxyphenyl)propane [bisphenol A], halogenatedbisphenol A, 4,4-dihydroxydiphenylmethane [bisphenol F],tris(4-hydroxyphenyl)propane, resorcin, tetrahydroxy-phenylethane,novolak-type polyvalent phenols, cresol-type polyvalent phenols and thelike.

Other resins usable as the epoxy resin (A) include1,2,3-tris(2,3-epoxypropoxy)propane, diglycidyl phthalate, glycidylhexahydrophthalate, glycidyl tetrahydrophthalate, dimer acid glycidylester, tetraglycidyl aminodiphenylmethane,3,4-epoxy-6-methylcyclohexylmethylcarboxylate, triglycidyl isocyanurate,3,4-epoxycyclohexylmethylcarboxylate, polypropylene glycol glycidylether and the like.

The ketimine compound (B) used in the composition of the invention is acuring agent for the epoxy resin (A) and is a polyamine compound havingat least one, preferably 1 to 6 primary amino groups blocked with acarbonyl compound. The "primary amino group blocked with a carbonylcompound" is a protected amino group which is readily hydrolyzed into afree primary amino group, for example in the presence of moisture, andis typically represented by the formula ##STR1## wherein R₁ is ahydrogen atom or a hydrocarbon group, and R₂ is a hydrocarbon group.

Examples of the hydrocarbon group include methyl, ethyl, propyl and likealkyl groups, cyclopropyl, cyclopentyl, cyclohexyl and like cycloalkylgroups, etc.

The polyamine compound may be aliphatic, alicyclic or aromatic. Thepolyamine compound needs to have a primary amino group which undergoes acuring reaction with the epoxy resin. Generally, it is advantageous forthe polyamine compound to have a primary amino group equivalent of about2,000 or less, preferably about 30 to 1,000. A suitable number averagemolecular weight of the polyamine compound is generally about 5,000 orless, preferably about 3,000 or less.

Examples of the polyamine compound include ethylenediamine,propylenediamine, butylenediamine, hexamethylenediamine,diethylenetriamine, triethylenetetramine, pentaethylenehexamine and likealiphatic polyamines; xylylenediamine, diaminodiphenylmethane,phenylenediamine and like aromatic polyamines; isophoronediamine,cyclohexyl-propylamine and like alicyclic polyamines; and polyamideshaving at least one primary amino group at the end of the molecule; etc.

Among the above polyamine compounds, particularly preferred are thosenot containing a secondary amino group in its molecule, i.e., thosehaving a ketimine of a primary amino group only, since such compoundshave good storage stability when mixed with an epoxy resin to form aone-packed resin composition. Accordingly, when a ketimine compoundhaving a secondary amino group in its molecule is used, the secondaryamino group is preferably converted to a tertiary amino group byreacting with the above epoxy resin, a monoepoxy compound such asethylene oxide or butyl glycidyl ether or the like.

Any of conventionally used ketones can be employed to obtain a ketimineof the polyamine compound. Examples of the ketones include acetone,methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone,cyclohexanone and the like. The ketimine compound for use in theinvention may be an aldimine obtained by reacting the polyamine compoundwith acetaldehyde, benzaldehyde or like aldehyde. The polyamine compoundcan be reacted with the ketone by a process known per se. Thequantitative proportions and conditions for the reaction are preferablyselected so that substantially all the primary amino groups in thepolyamine compound react with the ketone. It is generally advantageousfor easy progress of the reaction (dehydration) to use a ketone havinglow solubility in water and small steric hindrance, such as methylisobutyl ketone, methyl ethyl ketone or the like.

The ketimine compound (B) is preferably used in such a proportion thatthe amount of active hydrogen in the ketimine compound is 0.5 to 5.0equivalents, preferably 0.6 to 3.0 equivalent per equivalent of theepoxy group in the epoxy resin (A). If the amount of the active hydrogenis less than 0.5 equivalents, the curability of the resultingcomposition is insufficient. If the amount exceeds 5.0 equivalents, thecured film remains tacky and may have a problem in corrosion resistance.Accordingly, amounts outside the above range are not preferable.

The dehydrating agent (C) is used in the resin composition of theinvention chiefly for preventing hydrolysis of the ketimine compound andreaction of the hydrolyzate with the epoxy resin. The dehydrating agentremoves moisture from the composition by absorbing or reacting withwater in advance.

Conventional dehydrating agents can be used as the dehydrating agent (C)without limitations. Typical examples include the following:

(1) Powdery and highly porous metal oxides or carbides such as syntheticsilica, activated alumina, zeolite, activated carbon and the like.

(2) Calcium compounds having a formulation CaSO₄, CaSO₄. 1/2H₂ O, CaO orthe like, for example, calcined gypsum, soluble gypsum, quick lime andthe like.

(3) Metal alkoxides such as aluminum isopropylate,aluminum-sec-butylate, tetraisopropyl titanate, tetra-n-butyl titanate,zirconium-2-propylate, zirconium-n-butylate, ethyl silicate and thelike.

(4) Silane coupling agents such as methyltrimethoxysilane,ethyltrimethoxysilane, vinyltrimethoxysilane and the like.

(5) Organic alkoxy compounds such as methyl orthoformate, ethylorthoformate, dimethoxypropane and the like.

(6) Monofunctional isocyanates such as methyl isocyanate, ethylisocyanate, propyl isocyanate, additive TI (trade name, tolylenemonoisocyanate manufactured by Sumitomo-Bayer Urethane Co., Ltd.) andthe like.

The above dehydrating agents can be used singly or as a mixture of twoor more. The amount of the dehydrating agent (C) to be used variesaccording to the water content of the composition and the absorbing oradsorbing ability and reactivity of the dehydrating agent. Generally, itis suitable to use the dehydrating agent (C) in a proportion of about0.1 to 25 wt. parts, preferably 0.2 to 15 wt. parts per 100 wt. parts ofthe total-solid content weight of the components (A), (B) and (D) of thecomposition. When the composition further contains a pigment, theproportion of the dehydrating agent may be increased in consideration ofthe water content of the pigment. If the dehydrating agent is used in aproportion less than 0.1 wt. parts, the resulting composition tends tohave insufficient storage stability, whereas more than 25 wt. parts ofdehydrating agent may adversely affect the film properties. Thus,proportions outside the above range are not preferable.

The resin composition of the invention essentially contains, as acomponent (D), at least one modified epoxy resin (d-1) selected amongurethane-modified epoxy resins, amine-modified epoxy resins and dimeracid-modified epoxy resins and/or a resin (d-2) which has a softeningpoint of 60° C. or above and is selected among xylene resins, ketoneresins, coumarone resins and petroleum resins. The component (D) enablesformation of a coating excellent in adhesion, drying characteristics andthe like, and imparts excellent storage stability to the one-packedresin composition. In particular, the modified epoxy resin (d-1) ispreferred since it improves adhesion of the coating to various materials(iron, nonferrous metals, nonmetals and the like).

The modified epoxy resin (d-1) has considerably lower reactivity withthe polyamine compound than the epoxy resin (A). Since the reactionbetween the epoxy resin (A) and the polyamine compound proceeds at avery high rate, the modified epoxy resin (d-1) substantially does notparticipate in the curing reaction, although it has film formability.The composition containing the modified epoxy resin (d-1) but notcontaining the epoxy resin (A) has poor recoatability (repairability)and thus is not desirable.

Urethane-modified epoxy resins are preferred as the modified epoxy resin(d-1) since they impart a long-term storage stability to thecomposition. Examples of the urethane-modified epoxy resins includethose prepared by reacting a polyisocyanate or monoisocyanate compoundwith an amine-added epoxy resin obtained by reacting an amine with anepoxy resin. The epoxy resin used for preparing the urethane-modifiedepoxy resin may be any of those exemplified as the epoxy resin (A).Examples of the amine include alkanolamines, aliphatic amines, aromaticamines, alicyclic amines and the like. Usable polyisocyanate compoundsinclude known aliphatic, aromatic or alicyclic polyisocyanate compoundsand the like. Usable monoisocyanate compounds include those obtained byreacting phosgene with an aliphatic or aromatic monoamine, thoseobtained by reacting a hydroxyl-containing compound with one isocyanategroup of a diisocyanate compound.

Amine-modified epoxy resins preferably usable as the modified epoxyresin (d-1) are, for example, those obtained by addition-polymerizing anepoxy resin with a polyvalent phenol such as bisphenol A to obtain anepoxy resin having a desired molecular weight and then reacting theobtained resin with an alkanol amine (monoethanolamine, diethanolamine,triethanolamine or the like) for ring-opening the terminal epoxy group.The epoxy resin may be any of those exemplified as the epoxy resin (A).

Dimer acid-modified epoxy resins preferably usable as the modified epoxyresin (d-1) are, for example, epoxy resins having a desired molecularweight obtained by addition-polymerizing a polyvalent phenol such asbisphenol A and an adduct of an epoxy resin with a dimer acid (dimer ofan unsaturated acid such as oleic acid, linoleic acid, talloil fattyacid or the like). The epoxy resin may be any of those exemplified asthe epoxy resin (A).

The modified epoxy resin (d-1) has a number average molecular weight ofabout 2,000 to 65,000, preferably about 3,000 to 40,000, more preferablyabout 4,000 to 25,000. If the number average molecular weight is lessthan 2,000, the resulting coating film is reduced in adhesion and waterresistance. On the other hand, the modified epoxy resin (d-1) which hasa number average molecular weight exceeding 65,000 increases theviscosity of the composition and may adversely affects the workabilityand storage stability.

The modified epoxy resin (d-1), when employed, is suitably used in aproportion of 5 to 95 wt. parts, preferably 10 to 90 wt. parts per 100wt. parts of the epoxy resin (A), in terms of resin solid content. Ifthe proportion of the resin (d-1) is less than 5 wt. parts, theresulting composition has poor drying characteristics, whereas if theproportion exceeds 95 wt. parts, the resulting composition shows poorrecoatability when repaired.

The resin (d-2) is at least one resin having a softening point of 60° C.or above and selected among xylene resins, ketone resins, coumaroneresins and petroleum resins. The resin (d-2) preferably has a softeningpoint of about 70 to 170° C.

Preferred xylene resins for use as the resin (d-2) are, for example,those obtained by reacting meta-xylene with formaldehyde using acatalyst such as sulfuric acid and further reacting the obtained xyleneresin with a phenol such as phenol or ethylphenol or with rosin.

Preferred ketone resins for use as the resin (d-2) are, for example,those obtained by reacting a ketone such as cyclohexanone with aformaldehyde using a catalyst such as sulfuric acid.

Preferred coumarone resins for use as the resin (d-2) are, for example,those obtained by refining a 160 to 180° C. distillate fraction ofnaphtha (coumarone, indene, styrene or the like) and polymerizing therefined product by heating or with sulfuric acid or like catalyst.

Preferred petroleum resins for use as the resin (d-2) are, for example,those obtained by cationically polymerizing, with a Friedel-Craftscatalyst, C₅ or higher olefin residues from oil cracking.

The resin (d-2), when employed, is used in a proportion of 5 to 70 wt.parts, preferably 10 to 50 wt. parts per 100 wt. parts of the epoxyresin (A), in terms of resin solid content. If the proportion of theresin (d-2) is less than 5 wt. parts, the resulting composition has poordrying characteristics. If the proportion exceeds 70 wt. parts, theresulting composition shows poor recoatability when repaired and thefilm properties are adversely affected. Thus, proportions outside theabove range are not desirable.

The resin composition of the invention is an organic solvent typecomposition containing the above components (A) to (D).

Any of known organic solvents may be used which include toluene, xyleneand like aromatic hydrocarbons; acetone, methyl ethyl ketone, methylisobutyl ketone, diisobutyl ketone and like ketones; ethyl acetate,n-butyl acetate, isobutyl acetate and like esters; ethyl alcohol, propylalcohol, butyl alcohol and like alcohols; etc.

The resin composition of the invention may further contain any ofvarious additives, such as coloring pigment, extender pigment,anticorrosive pigment or like pigment, thickening agent, plasticizer,filler, dispersant or the like.

The present invention also provides a one-packed anticorrosive paintcomposition which contains, in addition to the above components (A) to(D), a zinc dust (E) in such an amount as to be present in a proportionof 20 to 95 wt. % in the heat-cured coating film. The paint compositionis suitable for coating a metallic surface, since it imparts highcorrosion resistance to the surface. The zinc dust (E) can be used incombination with another metal powder such as aluminum powder.

Examples of the zinc dust (E) include metal zinc dusts and metal zincalloy powders conventionally used in zinc-rich paints or zinc-richprimers. Among them, metal zinc dusts are preferred. It is suitable thatthe particles of the zinc dust are spherical and have a diameter ofabout 1 to 10 μm. The zinc dust is used usually in such an amount as tobe present in the heat-cured coating film in a proportion of 20 to 95 wt.%, preferably 70 to 90 wt. %. The cured film containing less than 20wt. % of the zinc dust does not have the contemplated corrosionresistance. If the zinc dust is used in such an amount as to be presentin the cured film in a proportion exceeding 95%, the storage stabilityand film formability of the composition are adversely affected. Thus,proportions outside the above range are not desirable.

For inhibiting white rust (zinc oxide) which may be caused by outdoorexposure, an aluminum powder is suitably used in combination with thezinc dust. Preferred as the aluminum powder are aluminum flakes having adiameter of about 1 to 150 μm. The aluminum powder may be of a leafingtype or non-leafing type. The aluminum powder, when employed, is addedpreferably in such an amount as to be present in the heat-cured coatingfilm in a proportion of about 1 to 20 wt. %, preferably 5 to 15 wt. %.

The resin composition or anticorrosive paint composition of theinvention can be used as a coating composition, a sealing agent or thelike. The composition can be applied to the surface of a substrate madeof metal (iron, aluminum, zinc or the like), wood, plastic, stone,slate, concrete, mortar or the like, or to a previously coated surfaceof these substrates. The composition can be applied by brush coating,spray coating, coating with any of various coaters or like commonmethod.

The amount of the resin composition or anticorrosive paint compositionto be applied is not limited. Generally, the composition is applied to adry film thickness of about 5 to 80 μm, preferably about 10 to 50 μm,when used as a clear composition, or to a dry film thickness of about 10to 150 μm, preferably about 25 to 120 μm, when used as a coloredcomposition.

The present invention further provides a coating method comprising thesteps of undercoating the surface of a substrate and conductingtopcoating, wherein the above one-packed epoxy resin composition orone-packed anticorrosive paint composition is used as the undercoatingcomposition.

The topcoating composition for use in the above coating method is notlimited and may be any of conventional topcoating compositions. Specificexamples are alkyd resin-based, chlorinated rubber-based, epoxyresin-based, silicon alkyd resin-based, urethane resin-based, siliconacrylic resin-based, fluorocarbon resin-based or like topcoatingcompositions.

When the one-packed epoxy resin composition of the invention is appliedto a substrate, the ketimine compound (B) contained as a curing agent isgradually hydrolyzed with moisture in the air or the like and reproducesa primary amino group. The primary amino group reacts with the epoxygroup in the epoxy resin (A), whereby the composition is cured andexhibits excellent corrosion resistance. In particular, the compositionof the invention is improved in drying characteristics and adhesion,since it contains the component (D), i.e., a specific modified epoxyresin or like resin which substantially does not participate in thecuring.

Accordingly, the epoxy resin composition of the invention comprising thecomponents (A) to (D) is suitable particularly as an undercoatingcomposition or a sealing agent, since it has good storage stability, isof a one-packed type which has good workability, and is excellent inadhesion, drying characteristics, repairability, overcoatability and thelike. The anticorrosive paint composition of the invention, whichfurther contains the zinc dust (E), can form a highly anticorrosivecoating film and is particularly useful as an undercoating compositionfor steels.

BEST MODE OF CARRYING OUT THE INVENTION

The following examples illustrate the present invention in furtherdetail, but by no means limit the scope of the invention. In theexamples, part(s) and percentages are all by weight.

EXAMPLE 1

Into a 2-liter container were placed 100 parts of epoxy resin solution A(*1), 175 parts of urethane-modified epoxy resin solution (*2), 0.5parts of vinyltrimethoxysilane as a dehydrating agent, 54 parts ofxylene, 36 parts of methyl isobutyl ketone and 10 parts of ketiminecompound A (*3). The mixture was stirred with a disperser to prepare aclear resin composition.

(*1) 70% toluene solution of "EPIKOTE 1001" (product of YUKA SHELL EPOXYCo., Ltd., solid epoxy resin having a number average molecular weight ofabout 900, two epoxy groups in its molecule and an epoxy equivalent of450 to 500)

(*2) "ARAKYD 9203" (product of ARAKAWA CHEMICAL INDUSTRIES Co., Ltd.,reaction product of amine-added epoxy resin with diisocyanate, having anumber average molecular weight of 13,000)

(*3) "VERSAMINE K-13" (product of Henkel Hakusui Corp., ketimine ofpolyethylene polyamine having a secondary amino group adducted with anepoxy resin, having an amino group equivalent of 381 to 461)

EXAMPLES 2 TO 7 AND COMPARATIVE EXAMPLE 1 TO 5

Clear resin compositions were obtained by following the procedure ofExample 1 and using the components shown in Table 1 in proportions(parts) shown therein.

(*4) "EPIKOTE 828" (product of YUKA SHELL EPOXY Co., Ltd., liquid epoxyresin having a number average molecular weight of about 380, two epoxygroups in its molecule and an epoxy equivalent of 184 to 194)

(*5) "Neopolymer 140" (product of NIPPON OIL Co., Ltd., petroleum resinhaving a solid content of 70%, a number average molecular weight of1,300 and a softening point of 145° C., solvent: xylene)

(*6) Adduct of the epoxy resin (*1) with a reaction product of 2 molesof diethylene triamine and 4 moles of methyl isobutyl ketone, having anumber average molecular weight of 1360, an amino group equivalent of230 and a solid content of 70%, solvent: methyl isobutyl ketone/toluene30/70)

                                      TABLE 1                                     __________________________________________________________________________              Example              Comparative Example                                      1  2  3  4  5  6  7  1  2  3  4  5                                  __________________________________________________________________________    Epoxy resin A (*1)                                                                      100                                                                              100                                                                              100                                                                              10    100                                                                              100                                                                              100      100                                                                              100                                Epoxy resin B (*4)                                                                                    100                                                                                       100                                       Urethane-modified                                                                         175                                                                             175                                                                              75                                                                               175                                                                              100                                                                              35                                                                               35                                                                                    100                                                                                  175                               epoxy resin (*2)                                                              Petroleum resin (*5)                                                                                     20                                                                               20                                              Vinyltrimethoxy-                                                                         0.5                                                                             0.8                                                                               0.5                                                                              0.5                                                                              0.5                                                                              0.5                                                                              0.8                                                                                      1.0                                   silane                                                                        Xylene         55         54                                                                    54                                                                               5                                                                                125                                                                               63                                                                              64                                                                               54                                                                              126                                                                                 54                                                                                54                               Methyl isobutyl                                                                              3736                                                                             36                                                                               3                                                                                 85                                                                               42                                                                              43                                                                               36                                                                               84                                                                                 36                                                                                36                               ketone                                                                        Ketimine compound A                                                                        10                                                                                10                                                                                1                                                                                40                                                                              10    10                                                                               40    10                                                                               10                                (*3)                                                                          Ketimine compound B                                                                         24                                                                                            24                                              (*6)                                                                          Solid content (%)                                                                            40                                                                               40                                                                               40                                                                               40                                                                                40                                                                              40                                                                               40                                                                               40                                                                               40                                                                               40                                                                               40                               Active hydrogen/                                                                          0.8                                                                            0.8                                                                              0.8                                                                              0.8                                                                              0.8                                                                              0.8                                                                              0.8                                                                              0.8                                                                              0.8                                                                                  0.8                                                                              0.8                               epoxy equivalent ratio                                                        __________________________________________________________________________

The compositions of Examples 1 to 7 and Comparative Examples 1 to 5 weretested for drying characteristics, storage stability and adhesion. Thetest methods are as follows.

Drying characteristics: Each test composition was applied to two tinplates (0.8×70×150 mm) using a film applicator with a clearance of 100μm to prepare two test plates. The obtained test plates were allowed tostand at 65% RH and 5° C. or 20° C. to measure the period necessary forthe coating surface to become tack dry to touch.

The results were rated as follows: A; within 8 hours, B; within 16hours, C; within 24 hours, D; within 48 hours, E; over 48 hours.

Storage stability: 800 g of the test composition was weight out, sealedup in a 1-liter cylindrical can and allowed to stand at 40° C. for onemonth. Then, the condition of the test composition was observed andrated as follows.

A; no abnormalities, B; thickened or precipitated, C; gelled Adhesion:Substrates used were a cold rolled steel plate (JIS G-3141), agalvanized steel plate (JIS G-3141 SPCC-SD) and an aluminum plate (JISH-4000 5052P), each measuring 0.8×70×150 mm, and a mortar plate (JISR-5201) measuring 10×100×200 mm. The test composition was applied to thesubstrates using a film applicator with a clearance of 100 μm and driedat 20° C. and 65% RH for 7 days to prepare test plates. The test plateswere allowed to stand in a humidity resistance tester (at 50° C. and atleast 95% RH) for 240 hours. Immediately after being taken out from thetester, the test plates were tested for adhesion by the X-cut tape testmethod prescribed in JIS K-5400-8.5.3.

The condition of the coating surface was rated as follows: A; noabnormalities, B; partially peeled off, C; peelings on the entiresurface.

The test results are shown in Table 2.

                  TABLE 2                                                         ______________________________________                                               Example         Comparative Example                                           1   2     3     4   5   6   7   1   2   3   4   5                      ______________________________________                                        Drying                                                                                                     characteristics                                                                5° C.   B  B  B  B  D  B  B  D  E                                     A  E  B                                                                       20° C.  A  A  B  A  C  B  B  C  D  A                                   D  A                                                                          Storage  A  A  A   A   A  A  A  C   C  A  B                                   B                                                                             stability                                                                     Adhesion                                                                      Cold rolled  A  A  A  A  A  A  A  A  B  A                                     A  B                                                                          steel plate                                                                   Galvanized   A  A  A  A  A  A  A  C  C  A                                     C  A                                                                          steel plate                                                                   Aluminum     A  A  A  A  A  A  A  B  B  A                                     B  A                                                                          plate                                                                         Mortar plate  A  A  A  B  A  A  A  A  A  B                                    A  A                                             ______________________________________                                    

EXAMPLE 8

Into a 2-liter container were placed 100 parts of epoxy resin solution A(*1), 175 parts of urethane-modified epoxy resin solution (*2), 30 partsof vinyltrimethoxysilane, 375 parts of magnesium silicate, 110 parts oftitanium dioxide, 106 parts of xylene and 71 parts of methyl isobutylketone. The mixture was stirred with a disperser and dispersed in a sandmill [JIS K-5400, fineness of dispersion, distribution chart method(graining: less than 60 μm)]. Thereafter, 10 parts of ketimine compoundA (*3) was added, and the resulting mixture was stirred with a disperserto obtain a colored resin composition.

EXAMPLES 9 TO 13 AND COMPARATIVE EXAMPLES 6 TO 9

Colored resin compositions were prepared by following the procedure ofExample 8 and using the components shown in Table 3 in proportions(parts) shown therein.

                                      TABLE 3                                     __________________________________________________________________________               Example           Comparative Example                                         8  9  10 11 12 13 6  7  8  9                                       __________________________________________________________________________    Epoxy resin A (*1)                                                                       100                                                                              100                                                                              10 100                                                                              100                                                                              100                                                                              100   100                                                                              100                                     Urethane-modified epoxy                                                                     175                                                                            175                                                                             160                                                                               12         100                                                                                  175                                    resin (*2)                                                                    Petroleum resin (*5)                                                                                   20                                                                                20                                               Vinyltrimethoxysilane                                                                      30                                                                               30                                                                              30                                                                                30                                                                               30                                                                               30                                                                                    30                                        Magnesium silicate                                                                           375                                                                             100                                                                               100                                                                              170                                                                               170                                                                             200                                                                              114                                                                              200                                                                              375                                    Titanium dioxide                                                                             11010                                                                            32                                                                                32                                                                               51                                                                                51                                                                              60                                                                               34                                                                              60                                                                                110                                   Xylene         106         106                                                                  45                                                                                29                                                                               75                                                                                75                                                                              90                                                                               25                                                                              90                                                                                106                                   Methyl isobutyl ketone                                                                    71                                                                                71                                                                              30                                                                                20                                                                               50                                                                                50                                                                              60                                                                               15                                                                              60                                                                                 71                                   Ketimine compound A                                                                           0                                                                                1                                                                                10                                                                              10    10                                                                                  10                                                                               10                                     (*3)                                                                          Ketimine compound B                                                                         24            24                                                (*6)                                                                          Solid content (%)                                                                           65                                                                             65                                                                               50                                                                               65                                                                               65                                                                               62                                                                               65                                                                               65                                                                               65                                                                               65                                     Active hydrogen/                                                                            0.88                                                                             0.8                                                                              0.8                                                                              0.8                                                                              0.8                                                                              0.8                                                                                  0.8                                                                              0.8                                    epoxy equivalent ratio                                                        __________________________________________________________________________

The compositions of Examples 8 to 13 and Comparative Examples 6 to 9were tested for drying characteristics, storage stability, adhesion andcorrosion resistance. The drying characteristics, storage stability andadhesion were tested by the above methods. The corrosion resistance wastested by the following method.

Corrosion resistance: Each test composition was applied to a polishedsteel plate measuring 0.8×70×150 mm using a film applicator with aclearance of 100 μm. The coating was dried at 20° C. and 65% RH for 7days to obtain a test plate. X-cut flaws were made on the coatingsurface of the test plate with a knife. The resulting test plate wassubjected to a 240-hour salt spray test at 35° C. and then checked forrust and blister.

The condition of the coating surface was rated as follows: A; noabnormalities, B; partially rustered or blistered, C; entirely rusted orblistered.

The results are shown in Table 4.

                  TABLE 4                                                         ______________________________________                                                                 Comparative                                                     Example        Example                                                        8   9     10    11  12  13  6   7   8   9                          ______________________________________                                        Drying                                                                        characteristics                                                                5° C.                                                                               B     B     B   B    B   B   D  A    E   B                      20° C.                                                                                  A   A     A   B  A    A   A  A    B   A                      Storage stability                                                                          A     A     A   B   A   A   C   A   B   B                        Adhesion                                                                      Cold rolled steel plate                                                                            A     A   A  A    A   A  A    A   A                      Galvanized steel plate                                                                             A     A   A  A    A   C  A    C   A                      Aluminum plate                                                                                     A     A A                                                                               A  A    A   B  A    B   A                      Mortar plate         A     A   A  A    A   A  B    A   A                      Corrosion resistance                                                                               A A   A   A  A    A   A  A    A   A                      ______________________________________                                    

EXAMPLES 14 TO 17

A mortar plate measuring 10×100×200 mm was brush-coated with thecomposition of Example 1 as an undercoating composition to a dry filmthickness of about 30 μm. The coating was dried at 20° C. and 65% RH for24 hours. Each of the topcoating compositions shown in Table 5 wasapplied to the undercoat and dried at 20° C. and 65% RH for 7 days toobtain a test plate.

EXAMPLES 18 TO 21 AND COMPARATIVE EXAMPLES 10 TO 13

Test plates were prepared by following the procedure of Example 14 andusing the undercoating compositions and topcoating compositions shown inTable 5.

The test plates obtained in Examples 14 to 21 and Comparative Examples10 to 13 were tested for overcoatability and recoatability(repairability) by the following methods.

Overcoatability: An adhesion test was carried out by the X-cut tape testmethod prescribed in JIS K-5400 8.5.3.

The results were rated as follows: A; no abnormalities, B; peelings onpart of the topcoating surface, C; peelings on the entire topcoatingsurface.

Recoatability: Test plates were prepared by following the procedures ofthe above Examples and Comparative Examples with the exception that thedrying period after applying the topcoating composition was changed to24 hours. X-cut flaws reaching the substrate were made on the testplate, and the resulting surface was recoated with each of theundercoating compositions. Then, the condition of the coating surfacewas observed and rated as follows: A; no abnormalities, B; partiallyshrinked, C; shrinkage on the entire surface.

The results are shown in Table 5.

                  TABLE 5                                                         ______________________________________                                                Example                                                                         14     15      16    17    18    19                                 ______________________________________                                        Undercoating                                                                                  Ex.1                                                                            Ex.1     Ex.1                                                                              Ex.1   Ex.6 Ex.6                               composition                                                                   Topcoating                                                                                         II     III                                                                               IV      I      II                             composition                                                                   Overcoatability                                                                             A      A       A    A      A     A                              Recoatability                                                                                 A                                                                                  A       A    A      A     A                              ______________________________________                                                Example  Comparative Example                                                    20     21      10    11    12    13                                 ______________________________________                                        Undercoating                                                                                  Ex.6                                                                            Ex.6    Comp.                                                                              Comp.  Comp.                                                                               Comp.                             composition                                                                                                 Ex.3                                                                           Ex.3   Ex.3  Ex.3                              Topcoating                                                                                        IV      I     II   III    IV                              composition                                                                   Overcoatability                                                                             A      A       A    A      A     A                              Recoatability                                                                                 A                                                                                  A       C    A      C     C                              ______________________________________                                    

In Table 5, the topcoating compositions I, II, III and IV are asfollows.

Topcoating composition I: Chlorinated rubber-based organic solvent typecoating composition "CLEAN RABATECT", product of KANSAI PAINT Co., Ltd.

Topcoating composition II: Epoxy resin-based organic solvent typecoating composition "ESCO", product of KANSAI PAINT Co., Ltd.

Topcoating composition III: Polyurethane resin-based organic solventtype coating composition "RETAN 6000", product of KANSAI PAINT Co., Ltd.

Topcoating composition IV: Fluorocarbon resin-based organic solvent typecoating composition "KANPE FRON HD", product of KANSAI PAINT Co., Ltd.

EXAMPLES 22 TO 26

A steel plate measuring 0.8×175×150 mm was brush-coated with thecomposition of Example 8 to a dry film thickness of about 50 μm, and thecoating was dried at 20° C. and 65% RH for 24 hours. The coating wasfurther brush-coated with each of the topcoating compositions shown inTable 6 to a dry film thickness of about 30 μm, and the coating wasdried at 20° C. and 65% RH for 7 days, giving a test plate.

COMPARATIVE EXAMPLES 14 TO 18

Test plates were obtained by following the procedure of Example 22 andusing the undercoating compositions and topcoating compositions shown inTable 6.

The test plates of Examples 22 to 26 and Comparative Examples 14 to 18were tested for overcoatability and recoatability (repairability) by theabove methods.

The results are shown in Table 6.

                  TABLE 6                                                         ______________________________________                                                Example                                                                         22       23      24     25    26                                    ______________________________________                                        Undercoating                                                                                 Ex.8                                                                                Ex.8   Ex.8    Ex.8                                                                               Ex.8                                 composition                                                                   Topcoating                                                                                       I                                                                                 II     III    IV    V                                  composition                                                                   Overcoatability                                                                             A        A       A       A                                                                                  A                                 Recoatability                                                                                 A      A       A       A                                                                                  A                                 ______________________________________                                                Comparative Example                                                             14       15      16     17    18                                    ______________________________________                                        Undercoating                                                                                 Comp.                                                                              Comp.  Comp.   Comp.                                                                              Comp.                                 composition                                                                                  Ex.7                                                                                Ex.7   Ex.7    Ex.7                                                                                Ex.7                                Topcoating                                                                                       I                                                                                 II     III    IV    V                                  composition                                                                   Overcoatability                                                                             A        A       A       A                                                                                  A                                 Recoatability                                                                                 C      A       C       C                                                                                  C                                 ______________________________________                                    

In Table 6, the topcoating compositions I, II, III and IV are asindicated above, and the topcoating composition V is as follows.

Topcoating composition V: Alkyd resin-based organic solvent type coatingcomposition "SD MARINE H", product of KANSAI PAINT Co., Ltd.

EXAMPLES 27 TO 34 AND COMPARATIVE EXAMPLES 19 TO 21

Anticorrosive paint compositions (zinc-rich paints) were prepared byfollowing the procedure of Example 8 and using the components shown inTable 7 in proportions shown therein. In Table 7, (*7) to (*9) indicatethe following.

(*7) "ALMIPASTE #50-635" (60% mineral spirit paste of aluminum powder,product of TOYO ALUMINIUM K.K.)

(*8) "TALEN 7200-20" (anti-sagging agent, product of KYOEISHA CHEMICALCo., Ltd.)

(*9) "TOHMIDE 225E", (comparative curing agent, product of FUJI KASEICo., Ltd.)

                                      TABLE 7                                     __________________________________________________________________________                Example                  Comp. Ex.                                            27 28 29 30 31 32  33 34 19 20  21                                __________________________________________________________________________    Epoxy resin A (*1)                                                                        100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100 100                                                                              100                                                                              100                                                                              100 100                               Urethane-modified epoxy                                                                        75                                                                               75                                                                               75                                                                               75                                                                               75                                                                                 75                                                                              75                                                                               75                                                                              75                                   resin (*2)                                                                    Vinyl trimethoxysilane                                                                         30                                                                               30                                                                               30                                                                               30                                                                               30                                                                                 30                                                                              30                                                                               30                                                                              30                                   Magnesium silicate                                                                             46  46                                                                           46                                                                               46                                                                               46                                                                               46                                                                                240                                                                              46                                                                              500                                                                              29    35                             Zinc dust       846          846                                                                 496                                                                              766                                                                              766                                                                              1330                                                                              652                                                                              596                                                                              114                                                                              3523                                                                              645                              Aluminum paste (*7)                                                                                 123                                                                              123                                                                              148                                                                                   385                                       Fatty acid amide wax (*8)                                                                    5                                                                                5                                                                                5                                                                                5                                                                                5                                                                                 5                                                                                5                                                                                5                                                                                5                                                                                5                                                                                  5                             Xylene           41              41                                                                5                                                                               15                                                                               15                                                                                76                                                                               41                                                                               16                                                                              229                                                                              1845                                                                               59                              Methyl isobutyl ketone                                                                         27                                                                                3                                                                               10                                                                               10                                                                                50                                                                               27                                                                               10                                                                              115                                                                               922                                                                               39                              Ketimine compound A (*3)                                                                     10                                                                                 10                                                                               10                                                                                    10                                                                              10                                                                               10                                                                               10                                                                               10                                  Ketimine compound B (*6)                                                                          4       24                                                Polyamide (*9)                                                                                                            14                                Solid content (%)                                                                              85   85                                                                          85                                                                               85                                                                               84                                                                                85                                                                               85                                                                               76                                                                               62                                                                               56                                                                                 85                             Active hydrogen/epoxy                                                                         0.8.8                                                                            0.8                                                                              0.8                                                                              0.8                                                                               0.8                                                                              0.8                                                                              0.8                                                                              0.8                                                                              0.8                                                                                0.8                             equivalent                                                                    Content in heat-cured                                                         coating film                                                                  Zn content (%)                                                                                 84      84                                                                       76                                                                               76                                                                               76                                                                                84                                                                               65                                                                               60                                                                               16                                                                               96                                                                                 84                             Al content (%)                                                                                      8    7                                                                               6      25                                        __________________________________________________________________________

The paint compositions of Examples 27 to 34 and Comparative Examples 19to 21 were tested for storage stability, corrosion resistance andovercoatability. The storage stability was tested by the above method,and the corrosion resistance and overcoatability were tested as follows.

Corrosion resistance: The test composition was diluted with 15% (outerpercentage) of xylene and air-sprayed to a steel plate to a dry filmthickness of 50 μm. The coating was dried at 20° C. and 65% RH for 7days to obtain a test plate. The steel plate used had been sandblasted(near-white metal blast cleaning according to ISO Sa2.5) or treated witha power tool (power tool cleaning according to ISO St3). X-cut flawswere made on the coating surface of the test plate with a knife. Then,the test plate was subjected to a 2,000-hour salt spray test at 35° C.and checked for rust.

The condition of the coating surface was rated as follows: A; noabnormalities, B; red rust on part of the surface, C; rust on the entiresurface. The test plate was checked also for white rust (zinc oxide).Overcoatability: The test composition was diluted with 15% (outerpercentage) of xylene, and air-sprayed to the sandblasted steel plate toa dry film thickness of 50 μm. The coating was dried at 20° C. and 65%RH, and brush-coated with "EPOMARINE" as a topcoating composition(product of KANSAI PAINT Co., Ltd., an epoxy resin-based organic solventtype coating composition) to a dry film thickness of about 30 μm. Theresulting plate was dried at 20° C. and 65% RH for 7 days to obtain atest plate. The test plate was tested for overcoatability by the abovemethod.

The results are shown in Table 8.

                  TABLE 8                                                         ______________________________________                                                    Example                                                                         27       28     29     30  31                                   Storage stability                                                                                      A        A    A    A                                 ______________________________________                                        Corrosion resistance                                                          Sandblasted steel plate                                                                        A       A        A    A    A                                 Occurence of white rust                                                                     Yes      Yes      Yes  No    No                                 (zinc oxide)                                                                  Power tool-treated Steel                                                                      A        A        A    A    A                                 plate                                                                         Occurence of white rust                                                                     Yes      Yes      Yes  No    NO                                 (Zinc oxide)                                                                  Overcoatability                                                                                         AA     A     A    A                                 ______________________________________                                                   Example    Comp.Ex.                                                             32    33       34  19    20   21                                 Storage stability                                                                                  A A      A   A     B    C                                ______________________________________                                        Corrosion resistance                                                          sandblasted steel plate                                                                      A     A        A   C     A    A                                Occurence of white rust                                                                    No    Yes       No Yes   Yes   Yes                               (zinc oxide)                                                                  Power tool-treated steel                                                                    A      B        B   C     B    A                                plate                                                                         Occurence of white rust                                                                    No    Yes       No Yes   Yes   Yes                               (zinc oxide)                                                                  Overcoatability                                                                                    A   A    A   A     A    A                                ______________________________________                                    

We claim:
 1. A one-packed epoxy resin composition comprising:(A) anepoxy resin having two or more epoxy groups in the resin molecule andsaid epoxy resin having a number average molecular weight of 250 to4,500, (B) a ketimine compound, (C) a dehydrating agent, and (D) atleast one epoxy resin (d-1) selected among urethane-modified epoxyresins prepared by reacting a polyisocyanate or monoisocyanate compoundwith an amine-added epoxy resin; amine-modified epoxy resins obtained byaddition-polymerizing an epoxy resin with a polyvalent phenol such asbisphenol A to obtain an epoxy resin having a desired molecular weightand then reacting the obtained resin with an alkanol amine; and dimeracid-modified epoxy resins obtained by addition-polymerizing apolyvalent phenol such as bisphenol A and an adduct of an epoxy resinwith a dimer acid; and/or a resin (d-2) which has a softening point of60° C. or above and is at least one member selected among xylene resinsobtained by reacting meta-xylene with formaldehyde using a catalyst suchas sulfuric acid and further reacting the obtained xylene resin with aphenol or a rosin; ketone resins obtained by reacting a ketone such ascyclohexanone with a formaldehyde using a catalyst such as sulfuricacid; coumarone resins obtained by refining a 160 to 180° C. distillatefraction of naphtha and polymerizing the refined product by heating orwith sulfuric acid; and petroleum resins obtained by cationicallypolymerizing, with a Friedel-Crafts catalyst, C₅ or higher olefinresidues from oil cracking.
 2. A composition according to claim 1 whichcontains the ketimine compound (B) in such a proportion that the amountof the active hydrogen in the ketimine compound is 0.5 to 5.0equivalents per equivalent of the epoxy group in the epoxy resin (A). 3.A composition according to claim 1 which contains the dehydrating agent(C) in a proportion of 0.1 to 25 wt. parts per 100 wt. parts of thetotal solid content weight of the components (A), (B) and (D) of thecomposition.
 4. A composition according to claim 1 which contains theresin (d-1) as the component (D) in a proportion of 5 to 95 wt. partsper 100 wt. parts of the epoxy resin (A), in terms of resin solidcontent.
 5. A composition according to claim 1 which contains the resin(d-2) as the component (D) in a proportion of 5 to 70 wt. parts per 100wt. parts of the epoxy resin (A), in terms of resin solid content.
 6. Aone-packed anticorrosive paint composition comprising:(A) an epoxy resinhaving two or more epoxy groups in the resin molecule and said epoxyresin having a number average molecular weight of 250 to 4,500, (B) aketimine compound, (C) a dehydrating agent, and (D) at least one epoxyresin (d-1) selected among urethane-modified epoxy resins prepared byreacting a polyisocyanate or monoisocyanate compound with an amine-addedepoxy resin; amine-modified epoxy resins obtained byaddition-polymerizing an epoxy resin with a polyvalent phenol such asbisphenol A to obtain an epooxy resin having a desired molecular weightand then reacting the obtained resin with an alkanol amine: and dimeracid-modified epoxy resins obtained by addition-polymerizing apolyvalent phenol such as bisphenol A and an adduct of an epoxy resinwith a dimer acid; and/or a resin (d-2) which has a softening point of60° C. or above and is at least one member selected among xylene resinsobtained by reacting meta-xylene with formaldehyde using a catalyst suchas sulfuric acid and further reacting the obtained xylene resin with aphenol or a rosin; ketone resins obtained by reacting a ketone such ascyclohexanone with a formaldehyde using a catalyst such as sulfuricacid; coumarone resins obtained by refining a 160 to 180° C. distillatefraction of naphtha and polymerizing the refined product by heating orwith sulfuric acid; and petroleum resins obtained by cationicallypolmerizing, with a Friedel-Crafts catalyst C₅ or higher olefin residuesfrom oil cracking, and (E) a zinc dust in such an amount as to bepresent in a proportion of 20 to 95 wt. % in the heat-cured coatingfilm.
 7. A coating method comprising the steps of:undercoating thesurface of a substrate with the one-packed epoxy resin compositionaccording to claim 1; and applying a topcoating composition.
 8. Acoating method comprising the steps of:undercoating the surface of asubstrate with the one-packed anticorrosive paint composition accordingto claim 6; and applying a topcoating composition.